The Apartment star was already a big fan of the show and when she first met all the cast she made a beeline for James-Collier - only to give him a piece of her mind about footman Thomas's bad behaviour.

Shirley MacLaine as Martha Levinson in the third series of Downton Abbey. Credit: ITV/PA Wire

James-Collier revealed: "It was a completely surreal experience. On the first day the staff are greeting her outside the front of the house. And at the rehearsals she got out the car, this Hollywood icon, and she was kind of looking for someone. And everyone was there, the entire cast, and she went 'It's you!' pointing at me."And I did the classic 'She can't be talking to me', looked behind me but it's just hedges there, and I thought 'She can't be talking to the bush!'

"She came over to me and she's like 'The evil one! Why are you so evil?!'"And I was like 'Hello Shirley, nice to meet you, I'm Rob, how you doing?' and she was like 'Never mind that, why are you so evil?!'."She was a massive fan of the show, so it was great to see. She had no airs or graces. She was just quizzing us about our characters."The fact that she even knew who I was was just a bonus."

Laura Carmichael, who plays Lady Edith Crawley, confessed she and Michelle Dockery and Jessica Brown Findlay had to be reminded to act more natural around MacLaine as they were playing her granddaughters.Carmichael said: "When she arrived we had to be told by our director to not look so in awe - she's our grandmother."Me and Michelle and Jess were all stood there with our mouths open."She's a legend and it was a pinch yourself moment."